Objective: The purpose of this study was to compare uterine electromyography of patients delivering>24 hours from measurement with laboring patients<or=24 hours from measurement.
Study design: Fifty patients (group 1: labor, n=24; group 2: antepartum, n=26) were monitored using transabdominal electrodes. Group 2 was recorded at several gestations. Uterine electrical "bursts" were analyzed by power-spectrum from 0.34 to 1.00 Hz. Average power density spectrum (PDS) peak frequency for each patient was plotted against gestational age, and compared between group 1 and group 2. Frequency was partitioned into 6 bins, and associated burst histograms compared.
Results: Group 1 was significantly higher than group 2 for gestational age (39.87+/-1.08 vs 32.96+/-4.26 weeks) and average PDS peak frequency (0.51+/-0.10 vs 0.40+/-.03 Hz). Histograms were significantly different. A correlation coefficient of .41, with significance, was found with PDS vs gestation.
Conclusion: Uterine electromyography in antepartum patients is significantly lower than in laboring patients delivering<or=24 hours from measurement.